Question marks remain over the details of two of the biggest spending promises the Abbott government took to the September election as it negotiates with the states over the $5.5bn-a-year paid parental leave scheme and the national disability insurance scheme (NDIS).

At his first Council of Australian Governments (Coag) meeting with state premiers and chief ministers, the prime minister, Tony Abbott, said they were still working on how the paid parental leave scheme would be administered for state public servants.

Abbott said he had conducted the meeting as “a meeting of equals not of antagonists”, but as always, the commonwealth and the states had some different views.

The commonwealth, for example, wants the states to hand over the money they now spend on their own parental leave schemes, which the federal government would top up to provide its generous 26 weeks leave at a full replacement wage up to earnings of $150,000 a year. But the states are insisting the federal government give money to them to top up the schemes they already administer.

Abbott said there was time to work it out since the new scheme did not start until July 1, 2015.

But West Australian premier Colin Barnett insisted state public servants were state employees and the schemes would remain in the hands of the states.

“The commonwealth would prefer the states simply to hand over the money, that is not going to happen,” he said, suggesting the resolution might be a pooled or jointly administered system.

The prime minister and premiers also discussed the likely cost blowouts in the NDIS after information started coming in from the launch sites – now retitled “trial sites”.

The assistant minister for social services, senator Mitch Fifield, recently told the National Press Club the average cost of the 921 plans drawn up to 30 June was $46,290, compared with a forecast average cost of $34,969 per plan.

Abbott said all leaders remained committed to the NDIS but it had to be implemented in a “fair and sustainable way”.

“It does seem there has been higher than anticipated demand and higher than anticipated costs; we are all absolutely committed to the implementation of the NDIS … but we have got to implement it in a way which is fair and a way which is sustainable,” Abbott said.

“That is why we are closely monitoring these trials ... We all accept that people with serious disabilities need a much better deal in the future than they have had in the past.”

The Coag agenda also reflected the new prime minister’s determination to make a mark in Indigenous affairs.

Abbott has flagged the use of “truancy officers” and expanded income management as part of a fresh push to boost school attendance, especially in Indigenous communities.

The Northern Territory chief minister, Adam Giles, said apart from removing disincentives, he was also considering implementing “a few punitive measures to encourage parents to send their kids to school”.

Abbott said he and state and territory leaders agreed to step up efforts to ensure every child attended school every day, but the approach would differ depending on local circumstances.

“In some places, truancy officers might be the best way forward. In other places, maybe a community-based scheme might be the best way forward,” he said.

“We've already got forms of income management in place where families don't consistently send their children to school.”

The official Coag communique says it is unacceptable that school attendance for Indigenous children in some areas has gone backwards. Measures to improve attendance will include minimum school attendance benchmarks; publication of twice-yearly data on school attendance for all students broken down by Indigenous and non-Indigenous; and a “no excuses” messaging campaign. On-the-spot audits of attendance were also flagged.

Abbott said every child must be in school unless there was a very serious reason for not being there, because a good education was crucial to a good start in life.

“We all know that for far too long, too many excuses have been made for Indigenous kids in particular not being at school. This must stop. It must stop soon, so we will be working urgently together to ensure that all kids, Indigenous and non-Indigenous, all kids, whether they're living in metropolitan areas, regional areas or remote areas, do go to school every day.”

Asked about the attendance benchmarks, Abbott said the nation should be aiming for 100% but 90% would be “broadly satisfactory”.

“Really, if there is any child who is routinely absent from school, at the level of the school, and if necessary, at the level of the relevant enforcement authority, that's something that needs to be looked into, because I said on election night no one should be left behind.”

The communique also flags efforts to ensure the establishment of a permanent police presence in additional remote Indigenous communities.

The meeting agreed to pare back Coag meetings to just two a year, with the next one due to discuss the contentious issue of school funding and ways to make it easier for Australian couples to adopt children from overseas.

Labor has backed the streamlining of environmental assessments – but not the handover of final approval power to state governments, which is the Abbott government’s final aim.

Greens senator Larissa Waters said the deals “pave the way for Tony Abbott to abolish a 30-year-old federal safeguard for our most precious natural places and wildlife, established when Bob Hawke stepped in to save the Franklin from being dammed”.